[Qemu-devel] [PATCH v2 0/5] s390x: network boot

From:

Cornelia Huck

Subject:

[Qemu-devel] [PATCH v2 0/5] s390x: network boot

Date:

Thu, 23 Feb 2017 13:20:20 +0100

v1->v2:
- style enhancements for patch 3, as suggested by Thomas
If this looks fine (and I'd still like an ack for patch 1), I'd like
to get this into 2.9.
Original cover letter:
This patchset implements network boot for s390x. You need to build
a s390-netboot.img to actually perform the work (not included).
Basically, we add support for virtio-net devices into the ipl code
and update the ccw bios to handle this as well.
For the first patch (elf loading) I'd like to get an ack.
A s390-netboot.img can be built by bundling some shell scripts, busybox
and the kexec binary bundled into an initial ramdisk and append that to
a kernel image. An existing s390 system can be used as source.
The init process can be a simple shell script that mounts a few
essential filesystems, like /dev, /proc, /sys, ..., starts a DHCP client
(busybox udchpc) and then invokes another script to do the actual
network boot.
udchpc will invoke the script /usr/share/udhcpc/default.script in
response to DHCP server messages to configure interfaces. The sample
busybox default.script can be used for that, but needs to also extract
the DHCP options like the tftp server address and pass that on to the
boot script.
The boot script itself has to retrieve the PXELINUX configuration from
the tftp server as in [1], then retrieve the remote kernel and initial
ramdisk and finally use kexec to boot the network kernel.
In a nutshell:
1. Create a skeleton initramfs directory structure
2. Create the init script, the PXE boot scripts and the DHCP default
script
3. Copy kexec and its dependencies from the source system into the
initramfs
4. Copy virtio network and block modules from the source system into
the initramfs
5. Copy the busybox binaries into the initramfs
6. Build the ramdisk (in compressed CPIO format)
7. Concatenate the kernel image and the initial ramdisk
8. Update the 8 bytes at location 66568 with the offset value of the
ramdisk in the new binary, and the 8 bytes at location 66576 with the
size of the ramdisk. Both values need to be updated in binary, big
endian format.
[1]
http://www.syslinux.org/wiki/index.php?title=PXELINUX#Configuration_filename
Cornelia Huck (1):
pc-bios/s390-ccw.img: rebuild image
Farhan Ali (4):
elf-loader: Allow late loading of elf
s390x/ipl: Extend S390IPLState to support network boot
s390x/ipl: Load network boot image
pc-bios/s390-ccw: Use the ccw bios to start the network boot
hw/core/loader.c | 17 ++++++++-
hw/s390x/ipl.c | 90 +++++++++++++++++++++++++++++++++++++++++++++
hw/s390x/ipl.h | 5 ++-
hw/s390x/s390-virtio-ccw.c | 3 +-
hw/s390x/s390-virtio.c | 2 +
hw/s390x/s390-virtio.h | 1 +
include/hw/elf_ops.h | 13 +++++--
include/hw/loader.h | 13 ++++++-
pc-bios/s390-ccw.img | Bin 26392 -> 26456 bytes
pc-bios/s390-ccw/bootmap.c | 8 +++-
pc-bios/s390-ccw/iplb.h | 3 +-
pc-bios/s390-ccw/main.c | 20 +++++++---
pc-bios/s390-ccw/virtio.c | 1 +
pc-bios/s390-ccw/virtio.h | 1 +
14 files changed, 160 insertions(+), 17 deletions(-)
--
2.11.0